Skyline logging systems are cable logging systems used to harvest timber from hillsides which are too steep for tractor logging. Skyline logging systems utilize a carriage similar to a trolley, to yard (move) logs from the location where they are felled to the landing (a location where the logs are concentrated for loading onto trucks). During the inhaul phase of the operation, one end of the log is carried above ground level. An intermediate support for the skyline may be employed where there is a rise or hump or other obstruction between the tree felling area and the location to which the logs are transported to provide the necessary ground clearance.
Logging over an intermediate support has been performed since the early part of the present century. Since its inception, it has been used with standing skyline systems. These are systems which operate with the skyline anchored at one end while the other end is held in position with a brake. Once the skyline is laid in the intermediate support and raised up into position, it does not move longitudinally in the support. Thus, in the previously employed systems the intermediate support engages a stationary line. The invention can also be used with such standing skyline systems.
In more modern systems, the skyline is used to support both the carriage and the turn of logs. These systems operate uphill with the yarder located at the top of the hill and the skyline extending downhill from the yarder. The carriage returns to the log hooking area by gravity where the carriage engages a stop on the skyline. The stop operates a lock in the carriage which releases the mainline and lets it fall to the ground. When it is desired to hook logs in a new location, the stop must be moved either up or down the skyline to the desired location, which is very time consuming. In this system, a ball is used to operate the carriage locking mechanism. The ball is held on the mainline with a steel pin, which in turn wears the line at its point of contact.